|• Epimysium; connective tissue covering the muscle.• Muscle fibers are grouped into fascicles, covered by perimysium.• Endomysium; connective tissue covering each individual muscle fiber.• Sarcolemma; thin surface membrane of the muscle fiber.• Sarcoplasm ; semi-fluid plasm and intracellular content of the muscle fiber.• Myosin and Actin are myo-fibrils, arranged in parallel within the sarcoplasm, responsible for muscle fiber contraction.
• Myosin molecules are thick filaments.
• Thin filaments made of actin molecules bound to troponin and tropomyosin.
• A sarcomere is a sub-unit within the muscle fiber, capable of contraction. It consists of strands of actin and myosin arranged in parallel.
• Transverse tubule (T-tubule). Transverse orientation with relation to muscle fiber; structurally internal to the muscle fiber cell, but contains extracellular fluid. Muscle action potentials travel through T tubules to into the muscle.
• Longitudinal tubule ( Sarcoplamic reticulum); expand to form bulbous Terminale Cisternae at the junction with T-tubules. Longitudinal tubules do not contain sarcoplasm or extra-cellular fluid. Two Terminale Cisternaes and one interposed T-Tubule form a triad in longitudinal sections of muscle.